Addition of carbonmonoxide-hydrogen to unsaturated compounds



Dec. 6, 11949 R. N. sHlRAs 2,490,283

ADDITION OF CARBON MONOXIDE-HYDHOGEN T0 UNSATURATED COMPOUNDS Filed Feb. s, 1947 5cond Step Lqud In+zrmedia+e Product y h'wznor: Russell N. Shrs una Produci' Patented Dec. 1949 ADDITION F CARBONMONOXIDE-HYDRO GEN TO UNSATURATED COMPOUNDS Russell N. Shin-as, Oakland, C alii., assignor to Shell Development Company, San Francisco,

Calif., a corporation oi Delaware Application February 3, 1947, Serial No. 726,085

(Ul. 26o-632) 9 Claims.

This invention relates to an improvement in processes for the synthesis of various oxygenated compounds by the catalytic addition of carbon monoxide and hydrogen to unsaturated bonds of various organic reactants. The invention relates side reaction is, however, the hydrogenation oi in one more specic embodiment to the producappreciable portions of the unsaturated reactant tion of carbinols. A still more specc cmbodiprior to the desired addition of carbon monoxide. ment relates to the production of primary alco- The addition reaction is catalyzed by metal carhols by the addition of carbon monoxide and bonyls. The various metal carbonyls are in equi-- hydrogen to oleilns. lo librium or tend to be in equilibrium with metal llt is known that by the application of suitablev and the carbon monoxide under the reaction conditions and catalysts carbon monoxide and conditions so that there is at least some highly hydrogen may be caused to react with a variety active metal in the reaction zone. of organic compounds (U. S. 1,698,602, U. S. which also exerts a beneficial catalytic eiect, 1,743,214, U. S. 1,746,781, U. S. 1,889,251, U. S. l tends to catalyze the hydrogenation of the un- 1,900,829, U. S. 1,973,662, U. S. l2,327,066, U. S. saturated reactant, and, since under the condi- 2,402,133) to produce oxygenated products contions necessary for the carbon monoxide-hydrotaining an increased number of carbon atoms. gen addition this hydrogenation reaction takes The reaction appears to be general for unsatplace at an appreciable rate, a substantial urated hydrocarbons and unsaturated oxygen deamount of the reactant is simply hydrogenated rivatives thereof. (Unsaturated, as the term is to the corresponding saturated compound. This .herein used, is meant to indicate the presence of is not only undesirable as representing an apprean ethylenic bond or acetylenic bond.) (Petrociable waste of hydrogen and valuable reactants, leum Renner :503-504 (1946).) It is applicable but also since it results in a less pure'product. with unsaturated organic compounds containing 25 In order to minimize the above-mentioned unnitrogen, phosphorus, sulfur, halogen, arsenic. desired hydrogenation reaction it is the prac- Unsaturated compounds containing other eletice to carry out the process in two or more stages ments have not been suiiiciently investigated to and to use a carbon monoxide-hydrogen gas mixdetermine the extent of their applicability. Howture (synthesis gas) relatively concentrated in ever, it appears that at least those of the more 3U carbon monoxide and lean in hydrogen in the electro-positive elements such as the alkali metals first stage. and alkaline earth metals are applicable when containing a ratio of hydrogen to carbon mon in ester or salt form. oxide below about 1.5 to 1. A synthesis gas rich The reaction takes place readily at an ethylin hydrogen is then used in the last stage. As enic bond. When one molecule each of carbon will be appreciated, this requires production of monoxide and hydrogen are added, the product two synthesis gases of different compositions, or contains the aldehyde group. Thus the addition adjustment of the concentrations of separate reaction foren ethylenic bond is portions of synthesis gas. By far the most practical method hitherto known and the method C C-H hitherto employed to provide the desired synu (Il C0 't E CHO thesis gases is to produce a synthesis gas containing a. ratio of hydrogen to carbon monoxide When one molecule of carbon monoxide and two greater than 1.5 (as by the partial combustion'of molecules of hydrogen are added, the product natural gas) t0 Separate part 0f the gas into its contains the carbinol group. Thus the addition Components through the agency 0f Copper am reaction for an ethylenic bond is: monium formate, and then to reblend the separated components with the remainder of the syn- C 0 11 thesis gas to produce two syntheses gases of dif- CO mi CHZOH ferent and desired compositions suitable for the two stages of the process. l vttlhen steamispresentinthe reaction zone, some workable, it iS involved and the PIOCSSS iS 0f carboxylic acids are produced. doubtful economy except in the production of a While these reactions can be fairly well confew oxygenated DlOdllCS Which may be produced trqlled, they. occur at least to some extent simulfrom relatively inexpensive raw materials and taneously. Also, some secondary reactions usuce command a relatively high price ally take place with the formation of ketones. aldol condensation products, and esters as well as some polymerization products of the unsaturated reactants. By far the most damaging This metal,

The preferred synthesis gas is one While this method is It has now been found that the above-described process for the production of oxygenated products by addition of carbon monoxide and hydrogen may be more advantageously carriedy out in the manner hereinafter described wherein the unsaturated reactant is utilized for adjusting the compositions of the synthesis gas and is applied to the first and last stages of the process.

To describe and illustrate the invention, reference will be had to the attached drawings wherein two process flows are illustrated diagrammatically.

Referring to the drawing, Figure I, a synthesis gas containing hydrogen and carbon monoxide in a mol ratio above 1.5 to 1, and preferably about 2:1, is introduced via line I. This gas is compressed by compressor 2 to a suitable high pressure and then passed via line 3 to an absorption zone 4 wherein it is intimately contacted under absorption conditions with the liquid unsaturated reactant feed to the process. The pressure is between about 1500 and 4500 pounds per square inch and preferably approximately that used in the first step of the synthesis, for instance 2500 Y p. s. i. g. as compared to 2000 p. s. i. g. The temperature may be ordinary or normal temperature, for instance 27 C., but is preferably held below normal by suitable refrigeration. The maximum degree of refrigeration is limited only by the freezing point of the liquid. Preferred temperatures are between about C. and about 20 C.

The unsaturated reactant is introduced via line 5. After being brought up to the desired pressure by pump 6 it is passed to a. cooler 'l wherein it is cooled to the desired temperature. The cooled liquid is then introduced near the top of absorber 4 via line 8. This material may be any of the various unsaturated compounds, liquid under these conditions, applicable as reactants in the production of oxygenated compounds by the catalyzed addition of synthesis gas.

The amounts of synthesis gas and unsaturated reactant supplied to the absorption zone are preferably substantially the amount required for the subsequent synthesis, taking into account the extent of the reaction, the formation of side reaction products and the desirability of bleeding a small amount of gas from the synthesis system to prevent excessive accumulation of diluent gas.

The absorber 4 may be of any efficient conventional type such as a suitably packed tower or an absorber equipped with plates and bubble caps. Due to the unsaturated character of the reactant feed supplied to the absorber and the countercurrent method of contact, most of the carbon monoxide and part of the hydrogen are absorbed leaving a gas lean in carbon monoxide which is withdrawn via line 9. When an absorber of good leiiciency is used, the lean gas contains or less of -carbon monoxide. However, a lean gas containing somewhat more carbon monoxide, for instance up to 10%, issuitable in many cases and is more easily obtained.

The liquid product from the absorber is passed via line i0 to the first synthesis step. The lean gas is passed via line 9 to the second synthesis step.

If desired the conditions in absorber 4 may be adjusted to give synthesis gases of the desired compositions within the applicable ranges. However, control through adjustment of the conditions in the absorber is not necessary. Thus, the adjustment may be more easily accomplished by bypassing a portion of the original synthesis gas via line H and/or reblending ,a portion of the lean Bas via line l2 to the feed to the first synthesis step. Thus, for example, if it is desired that the lean gas contain less than 5% carbon monoxide with a given absorber under a given set of conditions, the synthesis gas feed to the absorber is adjusted to give this result and the remaining synthesis gas is by-passed via line Il. If on the other-hand, a synthesis gas of somewhat higher ratio of hydrogen to carbon monoxide is desired in the nrst synthesis step, some of the lean gas rich in hydrogen is passed to the iirst synthesis step via line I2.

As an example of operation according to the described process, the production of butyl alcohol may be cited. The unsaturated reactant is a refinery Ca fraction containing 35 mol per cent propylene. The synthesis gas is Iproduced by the partial combustion of methane with oxygen at about 1150* C. and consists of hydrogen and carbon monoxide in a mol ratio of about 2:1 along with small amounts of impurities. 'I'he desired feed to the rst step of the synthesis contains hydrogen, carbon monoxide and propylene in the mole ratio below 1.52121 and preferably about 1.4:1:1. The propane-propylene fraction is cooled sufciently to maintain the temperature in the absorber at about 18 C. The absorber is a plate absorber having the equivalent of 16 theoretical plates. 4The pressure in the absorber is maintained at about 3000 p. s. i. g. The first synthesis step is effected at a pressure of about 2700 p. s. i. g. and the second synthesis step is eected at a pressure of about 2500 p. s. i. g. A total of about 3.052 moles of synthesis gas per mole of propylene is fed to the system. Of this about 45% is fed to the absorber and the remainder is by-passed via line Il. 'Ihe liquid product from the absorber has the following approximate composition (mole basis) Hydrogen 1.438 Carbon monoxide 1.000 Propylene 1.000 Propane L 1.857

This product contains the desired reactants, is very close to the desired concentrations, and is fed to the rst synthesis step. 'I'he lean gas is passed directly to the second synthesis step.

In some cases, and particularly when reacting carbon monoxide and hydrogen with olens of high molecular weight, it is more advantageous to operate the process in the manner illustrated in Figure II. In this modification the liquid unsaturated reactant is recycled in part through the absorber and a low pressure flasher. In this modication greater concentrations of carbon monoxide may be obtained with less cooling.

Referring to the drawing, Figure II, the unsaturated reactant is introduced via line 20 near the top of the absorber 2 I, Synthesis gas, for instance obtained by the partial combustion of methane and containing hydrogen and carbon monoxide in a ratio of about 2:1, is introduced near the bottom of the absorber via line 22. A high pressure, such as 3000 p. s. i. g., is maintained in the absorber. The temperature in the absorber is room temperature or lower, for instance 5 C. or below. The desired temperature is obtained, as before. by cooling the liquid reactant. The lean gas from the top of the absorber is passed via line 23 to the second step ofthe synthesis process. If necessary or desired, this gas may be subjected to a conventional treatment to remove small amounts of carbon monoxide. The fat liquid is withdrawn from the bottom of the absorber via line 24. This stream 'is divided into tWo streams. One stream is passed, as before, directly to the i'irst step of the synthesis via line 25. The remainder is passed via line 21 through a pressure reduction valve 26 to a low pressure asher 28. The pressure in flasher 28 is materially lower than in the absorber and may be, for example, substantially atmospheric pressure. Gas released from the reactant in the low pressure absorber is compressed and passed l via line 29 to the rst synthesis step. The liquid is continuously withdrawn from the bottom of the low pressure iiasher and returned to the absorber via pump 30 and lines 3l and 20. As before, a portion of the 2: 1 synthesis gas may be bypassed via line 32 and commingled with the gas fed to the rst synthesis step.

A typical application of this modification of the process of the invention is in the production of nonyl alcohol from 2:1 synthesis gas and diisobutylene. For the first synthesis step one mol of carbon monoxide per mol of diisobutylene is used, and a synthesis gas having a ratio of hydrogen to carbon monoxide below 1.5:1 and preferably about 1.4:1 is desired. 'I'he absorber is again a plate absorber having the equivalent of 16 theoretical plates. The pressure in the absorber is maintained at about 2500 p. s. i. g. The temperature is maintained at about -18 C'. by cooling the liquid feed to the absorber. A total of about 3.048 mols of synthesis gas (2:1) per mol of diisobutylene uis supplied to the system. Of this about 1.41 mols is passed to the absorber and the remainder is by-passed .via line 32. The fat liquid from the absorberl has the following approximate composition (mol basis):

Hydrogen Carbon monoxide 0.460

Diisobutylene 5.735

Of this, about '75% is passed to the low pressure flasher operated at atmospheric pressure. Thus, about 4.785 mols of diisobutylene per mol of fresh diisobutylene feed is passed through the low pressure flasher and cycled to the absorber. The gas released is compressed and passed to the first synthesis step along with the remaining approximately 25% of the fat liquid. This gives the desired feed to the rst synthesis step. The ratio of carbon monoxide to hydrogen in the feed can be altered appreciably and controlled by variation and control of the proportion of the diisobutylene recycled,

The invention claimed is:

1. In a-process for the production of an oxyu genated compound by the catalyzed addition of carbon monoxide and hydrogen to an unsatu d rated reactant in two synthesis steps using a synthesis gas rich in carbon monoxide in the first step and a synthesis gas lean in carbon monoxide in the second step, the improvement which comprises supplying to the process a synthesis gas containing hydrogen and carbon monoxide in a mol ratio above 1.5:1, contacting said synthesis gas with the liquid unsaturated reactant under absorption conditions in an absorption zone, passing the liquid containing dissolved hydrogen and carbon monoxide from said absorption zone to the rst synthesis step and therein producing a'liquid intermediate synthesis product, passing said liq-v uid intermediate synthesis product to the second synthesis step, and passing the lean gasl from said absorption zone to the second synthesis step.

2. Process according to claim 1 in which the absorption zone is maintained under a pressure slightly higher than that prevailing in the reaction zone of the first synthesis step,y

3. Process according to claim 1 in which the absorption zone is maintained under a pressure between about 1500 and 4000 p. s. i. g.

4. Process according to claim 1 in which the absorption zone is maintained below normal temperatures by cooling the unsaturated reactant fed thereto.

Y 5. Process according to claim 1 in which sufliclent synthesis gas is by-passed around the ala-.- sorption zone to the iirst synthesis step so that the total amount of synthesis gas fed to the rst synthesis step is from 1 to about 1.5 moles per mole of unsaturated reactant fed, including that dissolved in the liquid.

6. Process according to claim 1 in which a portion of the liquid eiiiuent from the absorption zone is passed to a ashing zone maintained at a substantially reduced pressure to release dissolved gas and vthen recycled from said ashing zone to the absorption zone, and the gas released in said flashing zone is recompressed and passed to the first synthesis step.

7. Process according to claim 1 in which the unsaturated reactant is an oleiln.

8. Process according to claim 1 in which the unsaturated reactant fed to the absorption zone is an oleilnic petroleum fraction.

9. Process according to claim 1 in which the synthesis gas supplied to the process contains hy-4 drogen and carbon monoxide in a mole ratio of- The.l following references are of record in th le of this patent:

UNTED STATES PATENTS Number Name Date 2,327,065 H0918!! Allg. 17, 1943 Gresham et al. June 18, 1946 

